fix(ShareSheet): title slot not work

src/share-sheet/test/__snapshots__/demo.spec.js.snap

@@ -23,5 +23,12 @@ exports[`renders demo correctly 1`] = `
     </div>
     <!---->
   </div>
+  <div>
+    <div role="button" tabindex="0" class="van-cell van-cell--clickable">
+      <div class="van-cell__title"><span>显示分享面板</span></div><i class="van-icon van-icon-arrow van-cell__right-icon">
+        <!----></i>
+    </div>
+    <!---->
+  </div>
 </div>
 `;

src/share-sheet/test/__snapshots__/index.spec.js.snap

@@ -0,0 +1,14 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`cancel-text prop 1`] = `<button type="button" class="van-share-sheet__cancel">foo</button>`;
+
+exports[`description prop 1`] = `<span class="van-share-sheet__description">foo</span>`;
+
+exports[`title & description slot 1`] = `
+<div class="van-popup van-popup--round van-popup--bottom van-popup--safe-area-inset-bottom van-share-sheet" name="van-popup-slide-bottom">
+  <div class="van-share-sheet__header">
+    <h2 class="van-share-sheet__title">Custom Title</h2><span class="van-share-sheet__description">Custom Description</span>
+  </div>
+  <div class="van-share-sheet__options"></div><button type="button" class="van-share-sheet__cancel">取消</button>
+</div>
+`;